In known capacitors of the above-described type, in which the thin aluminum layers have surface resistances, that is resistances per square unit of approximately 3 ohms, a circular disintegration of the aluminum layer sets in if the average electrical field strength in the dielectric exceeds a predetermined value. This causes surface losses which lead to decreasing capacitance values. For a capacitor utilizing a polypropylene sheet as dielectric the deterioration of the aluminum surface starts at an effective field strength of approximately 40 V/.mu.m at a frequency of 50 Hz. In order to prevent this undesired decrease in capacitance in the known capacitors, smaller field strength are utilized then would otherwise be permitted by the dielectric. For example fluorescent lamp condensors with metallized polypropylene sheets as dielectric and with the known aluminum coatings are manufactured from sheets having a thickness of 8 .mu.m for nominal voltages of 220 to 250 volts at 50 Hz, even though thickness of 6 .mu.m would suffice for sufficiently thin aluminum layers having a surface resistance exceeding 3.5 ohms. However the resulting field strength would be too high because testing takes place at a voltage exceeding the nominal voltage by about 25%, thereby causing the above-mentioned deterioration of the aluminum layer. This deterioration therefore also causes higher costs for the capacitor and a greater volume then would otherwise be necessary.